During spinal fusion surgery and surgery to correct scoliosis, the curves of the spine are realigned. Particularly in scoliosis correction surgery this may involve relatively large translations of individual vertebrae to achieve the desired spinal alignment, the realigned vertebrae fixed in place by a combination of shaped rods and pedicle screws.
Prolonged degenerative disease processes and the distortions that occur as a result of severe scoliosis are such that the forces required to move the spinal column to the new curves are considerable. In addition, the translations required of each pedicle screw in order to match up to the shaped rod are often relatively large. These two factors render the matching of the screws with a rod to which they are to be connected during surgery difficult.
Various “rod approximating” devices have been designed in attempt to assist with this procedure. Such devices are connected to a screw to force a rod into the screw head. Many of these devices may be used during a single surgery with up to 20, 10 each side, connected to the screws in a scoliosis surgery.
However, the current rod approximating devices do not spread the force generated in re-shaping the spine evenly over all the screws. Due to their stiff construct they more typically load up two or at most three screws with the consequent force. This in turn risks pulling the screws out of the bone or weakening the screws' grip in the bone, which may in turn cause failure of the surgery or increased surgical complication intraoperatively.
There is a need, therefore, to address the problems associated with current devices used in rod reduction.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.